From owner-freebsd-arm@freebsd.org Fri Jan 27 02:28:12 2017 Return-Path: Delivered-To: freebsd-arm@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 29936CC32C7 for ; Fri, 27 Jan 2017 02:28:12 +0000 (UTC) (envelope-from ian@freebsd.org) Received: from pmta2.delivery6.ore.mailhop.org (pmta2.delivery6.ore.mailhop.org [54.200.129.228]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 0D48CFD7 for ; Fri, 27 Jan 2017 02:28:11 +0000 (UTC) (envelope-from ian@freebsd.org) X-MHO-User: 18e7ad05-e438-11e6-b3c1-c9f38144898e X-Report-Abuse-To: https://support.duocircle.com/support/solutions/articles/5000540958-duocircle-standard-smtp-abuse-information X-Originating-IP: 73.78.92.27 X-Mail-Handler: DuoCircle Outbound SMTP Received: from ilsoft.org (unknown [73.78.92.27]) by outbound2.ore.mailhop.org (Halon) with ESMTPSA id 18e7ad05-e438-11e6-b3c1-c9f38144898e; Fri, 27 Jan 2017 02:27:07 +0000 (UTC) Received: from rev (rev [172.22.42.240]) by ilsoft.org (8.15.2/8.15.2) with ESMTP id v0R2R3kg004814; Thu, 26 Jan 2017 19:27:03 -0700 (MST) (envelope-from ian@freebsd.org) Message-ID: <1485484023.30533.102.camel@freebsd.org> Subject: Re: BBB uarts & pps dts definitions From: Ian Lepore To: Tony Hain , freebsd-arm@freebsd.org Date: Thu, 26 Jan 2017 19:27:03 -0700 In-Reply-To: <041a01d2782d$bee11850$3ca348f0$@tndh.net> References: <03a801d2776e$cae997e0$60bcc7a0$@tndh.net> <1485400906.30533.54.camel@freebsd.org> <03bb01d2779d$45d6edd0$d184c970$@tndh.net> <03c101d277ae$70f142c0$52d3c840$@tndh.net> <1485445768.30533.68.camel@freebsd.org> <040101d27816$3f7547b0$be5fd710$@tndh.net> <1485466405.30533.96.camel@freebsd.org> <041a01d2782d$bee11850$3ca348f0$@tndh.net> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.18.5.1 FreeBSD GNOME Team Port Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 27 Jan 2017 02:28:12 -0000 On Thu, 2017-01-26 at 15:41 -0800, Tony Hain wrote: > > > > > -----Original Message----- > > From: Ian Lepore [mailto:ian@freebsd.org] > > Sent: Thursday, January 26, 2017 1:33 PM > > To: Tony Hain; freebsd-arm@freebsd.org > > Subject: Re: BBB uarts & pps dts definitions > > > > On Thu, 2017-01-26 at 12:53 -0800, Tony Hain wrote: > > > > > > Ian Lepore wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > snip > > > > > > > > > > [even more snip] > That makes some degree of sense based on what I am seeing, though that is a > very low input impedance on the BBB. I was expecting ~100k. My source is a > 555 on an ancient ttl/RS232 board I built because the 20 us pulse from the > GPS was too fast (between the slew rate of the 3232 and the DCD detection > window on the com port) to go with a simple level conversion. Sounds like it > might be best to do an active 3.3v driver at this point. > > Tony BTW, not related to the BB stuff... a while back I added "narrow pulse capture" support to uart(4) for CTS/DCD PPS capture, you can use it with pulses as narrow as 1uS, maybe even less on some hardware.  The tradeoff is that you can only capture assert edges, not clear.  The support goes back to 10.3 or so, details are in the uart(4) manpage. -- Ian